Snap: I've been made redundant for pretty much the same reason - refusing to pad the price of goods being sold via an agent to somewhere south of the equator by 6% so that it could be creamed off as 'commission',
If you sell via an agent and you have grounds to believe the agent is up to dodgy dealings, you can still be prosecuted for it, even if you haven't directly benefited from the corruption.
My mate John, ex-bootie, had a subbie bricky business. I went along to a site with him one time on the way to the pub - he was handing back drawings and giving in his written estimate. He came storming out of the porta-cabin with a face like thunder and eventually told me that the bloke said to him - "the last subbie offered me 5 grand for the job, what are you offering".